Method weight

balancer/weightedroundrobin/balancer.go:620–657

weight returns the current effective weight of the endpoint, taking into account the parameters. Returns 0 for blacked out or expired data, which will cause the backend weight to be treated as the mean of the weights of the other backends. If forScheduler is set to true, this function will emit met

(now time.Time, weightExpirationPeriod, blackoutPeriod time.Duration, recordMetrics bool)

// other backends. If forScheduler is set to true, this function will emit
// metrics through the metrics registry.
func (w *endpointWeight) weight(now time.Time, weightExpirationPeriod, blackoutPeriod time.Duration, recordMetrics bool) (weight float64) {
	w.mu.Lock()
	defer w.mu.Unlock()

	if recordMetrics {
		defer func() {
			endpointWeightsMetric.Record(w.metricsRecorder, weight, w.target, w.locality, w.clusterName)
		}()
	}

	// The endpoint has not received a load report (i.e. just turned READY with
	// no load report).
	if w.lastUpdated.Equal(time.Time{}) {
		endpointWeightNotYetUsableMetric.Record(w.metricsRecorder, 1, w.target, w.locality, w.clusterName)
		return 0
	}

	// If the most recent update was longer ago than the expiration period,
	// reset nonEmptySince so that we apply the blackout period again if we
	// start getting data again in the future, and return 0.
	if now.Sub(w.lastUpdated) >= weightExpirationPeriod {
		if recordMetrics {
			endpointWeightStaleMetric.Record(w.metricsRecorder, 1, w.target, w.locality, w.clusterName)
		}
		w.nonEmptySince = time.Time{}
		return 0
	}

	// If we don't have at least blackoutPeriod worth of data, return 0.
	if blackoutPeriod != 0 && (w.nonEmptySince.Equal(time.Time{}) || now.Sub(w.nonEmptySince) < blackoutPeriod) {
		if recordMetrics {
			endpointWeightNotYetUsableMetric.Record(w.metricsRecorder, 1, w.target, w.locality, w.clusterName)
		}
		return 0
	}

	return w.weightVal
}

type backendServiceKey struct{}